In cleaning up oil spills on water, it is often desirable to separate the oil from the water in order to minimize the needed storage capacity for the oil and to facilitate subsequent oil disposal. Further, providing for on-scene separation of water from the oil permits the use of high rate oil skimmers that are less efficient at rejecting water.
A problem common to many oil spills is debris floating in the oil or water. In icy water, the debris may be chunks of ice. A separator must be able to handle debris without becoming clogged.
A further problem in cleaning up oil spills is that clean-up equipment must in most cases be transported on some kind of vehicle, normally a road vehicle or a waterborne vessel. This means that the separator must be portable, meaning it ought to be lightweight and not overly large. Height, particularly, must be controlled because an overly tall separator would raise the center of gravity of a small boat or road vehicle to an unsafe height.
A number of types of oil-water separators are known, e.g., centrifugal, coalescing, and gravity. Separators of the latter, gravity type are inherently simple, as they involve no moving parts, but the large size and weight of the separating tanks required has conventionally limited their use to fixed sites, such as waste water treatment plants. E.g., U.S. Pat. Nos. 1,672,583; 2,820,550; 3,419,145; 3,517,815; 3,933,654; 4,049,553; and 4,132,652. One of these prior waste-water separators, Bolton et al. U.S. Pat. No. 3,517,815, shows a tank divided by vertical plates into a serpentine, horizontal flow path.